1. Field of the Invention
This invention relates to surgical fastening apparatus and specifically to an improved surgical fastening apparatus containing an interlock to prevent movement of the cam bar retainer during shipping or handling of the instrument.
2. Background of the Prior Art
Surgical fastening apparatus for placing gastro intestinal anastomoses are known in the art. Such apparatus are used for suturing gastric and intestinal walls with spaced parallel rows of longitudinally aligned staples or surgical fasteners. For example, Bobroy et al. (U.S. Pat. No. 3,079,606) discloses an instrument for suturing gastric and intestinal walls with metal staples by inserting the tips of the instrument into the lumens of the organs to be sutured through apertures in the walls of the organs. The apparatus comprises a two part frame, each part having finger like projections or forks which are inserted respectively into the apertures in the walls of the organs to be sutured. The frame parts are hinged together with the body tissue held between the forks. When the instrument is actuated, longitudinally moving cam bars contact staple drive members in one of the forks, thereby pushing the surgical staples through the body tissue and into an anvil in the opposite fork. A knife blade between the cam bars creates an incision between the parallel rows of staples. It should be noted, however, that the knife blade is an optional feature. The instrument may be used to fasten body tissue without creating an incision between the rows of staples.
Green et al. (U.S. Pat. No. 3,490,675) discloses an improved instrument of type discussed above, the improved instrument laying down double rows of staples on each side of the incision.
A further improvement in this type of instrument is disclosed in Green (U.S. Pat. No. 3,499,591). The further improved apparatus incorporates an improved structure for the staple-containing cartridge, the pusher assembly which includes the cam bars and knife, and the staple driving members. The contents of the above mentioned patents are incorporated by reference herein in their entirety.
During shipment of the apparatus from the supplier to the user, it may happen that jostling of the cargo during shipment causes the thrust knob and cam bar mechanism to move forward. This can cause premature firing of the staples.
A known shipping interlock is illustrated in FIG. 10, below wherein shipping interlock 190, which comprises a plate member attached to a stationary carrier 134, includes an aperture 191 in the plate. An integral member 146 initially projects from the cam bar retainer 138 through aperture 191. The projection 146 is fabricated from a deformable material such as plastic. To actuate the apparatus, the cam bar retainer 138 is moved distally to advance cam bar 132. This requires the top portion of projection 146 to be sheared off as the cam bar retainer 138 is pushed forward. The force required to shear off the top of projection 146 is easily applied by a surgeon, but higher than forces generally developed during jostling of cargo during shipment.
While the prior known shipping interlock has been useful, we have provided an alternative shipping interlock which functions in a different manner to prevent inadvertent movement of the actuation mechanism of the apparatus as would occur, for example, during shipping and transportation.